1. Field of the Invention
This invention relates to laminates and foam filled sheet products, both decorative and structural, and more particularly it relates to structurally rigid sheets of foam having glass fibers distributed substantially evenly throughout the foam. It also relates to a method for forming such a product.
2. Description of the Prior Art
The field of foamed resins is wide and the choice of resin is determined not only by cost and availability but also by properties such as flammability, friability, thermal conductance, appearance, ease in foaming and application and moisture resistance. And it is, of course, well-known to include fillers and additives to alter the properties of the foamed material.
Many attempts have been made to create structural laminates, particularly of foamed resins to be used for purposes of insulation as well as for wall and ceiling panels. Laminates have often been limited in the choice of foamed resins for this reason. Alternatively, foamed resins which are unsatisfactory in respect to certain properties have been made acceptable by the use of additives. These additives or fillers have had various disadvantages such as the toxic nature of halogen and/or phosphorus containing fire retardant additives. Self-supporting foamed laminates, such as the polystyrene and polyvinyl chloride, are also well-known, but have low structural strengths which limit the use of such laminates.
Laminates employing a core of batting material are also known in the art. Typically such materials suffer discontinuities and structural weaknesses.
It is therefore an object of this invention to create a strong laminate which is free of discontinuities.
It is a further object of this invention to form a laminate utilizing a foamed polymeric resin with a mat of long glass fibers to form a unique laminate of superior performance and of pleasing appearance.
Before laminates of this type can be used, however, it is necessary that they meet structural and fire safety standards.
Previous attempts to make similar structures utilizing foams have relied on the spongy character of a high loft batting into which a foam-forming resin was forced and then permitted to foam and expand at the same rate as the high loft fibrous batting material expanded. An example of this process applied to making a flexible foam filled batting material can be found in U.S. Pat. No. 3,617,594.
A distinct disadvantage is presented by using a high loft batting in that the batting may elastically recover faster than the foam-forming mixture expands, thereby producing voids or pockets within the resultant material, the pockets contributing directly to possible structural failure of the material when subjected to high heat conditions.
It is therefore an object of this invention to form a structural laminate using a low loft mat of long glass fibers, the mat being thin, substantially incompressible, yet expansible under the sole influence of the expansion of a foam-forming mixture which penetrates and completely fills the interstices between the fibers of the mat.
It is another object of this invention to create a structural laminate having improved fire resistant properties.
It is yet another object of this invention to produce a structural laminate having superior fire resistant properties, which would qualify for approval by the Factory Mutual Research Corporation, an independent risk certification firm.
A method of making a low loft mat which satisfies the functional and structural requirement of this invention is to be found in U.S. Pat. No. 2,609,320, provided certain limitations are placed on the method. For example, in a mat acceptable for use in a laminate according to this invention, the glass fibers are attached to one another by an amount of fiber binder sufficient to make the mat of glass fibers dimensionally stable but insufficient to fill the interstices between the glass fibers. Preferably, only a minimum amount of this fiber binder should be employed. Further, the mat should not be expanded or puffed up in thickness as is taught in U.S. Pat. No. 2,609,320 but rather should be of low loft such that pressure applied to the faces of the mat will not substantially reduce the thickness of the mat and such that the mat does not elastically recover to any appreciable amount when the pressure is released from the faces of the mat. Of course, any other method can be used which would result in a batt of glass fibers having a structure substantially the same as that produced by the method of U.S. Pat. No. 2,609,320 with these restrictions.